Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
7608878 | Journal of Chromatography A | 2018 | 8 Pages |
Abstract
In the present study, a new RI system for GCâ¯Ãâ¯GC was developed. Polyethylene glycols (PEGs) were used in combination with a simple linear regression, with n-alkanes as reference points for virtually unretained compounds and PEG homologs as reference compounds for second-dimension RIs (PEG-2I). The n-alkanes were assigned a PEG-2I of zero and the distance between consecutive PEG homologs from PEG-2 (diethylene glycol) and higher were assigned a PEG-2I value of 10. We used ethylene glycol and PEG-2 through PEG-10 as reference compounds, thereby covering a PEG-2I range from 20.0 for ethylene glycol, over 50.0 for diethylene glycol (PEG-2) to 130.0 for decaethylene glycol (PEG-10); additional PEGs can be added to cover a wider polarity range. The PEG-2I system was initially evaluated using a 30â¯mâ¯Ãâ¯0.25â¯mm non-polar (5% phenyl, 0.25â¯Î¼m film thickness) first-dimension column and a 1.6â¯mâ¯Ãâ¯0.18â¯mm polar (50% phenyl, 0.18â¯Î¼m film thickness) second-dimension column. This system was validated for use with non-polar first-dimension columns and a semi-polar (50% phenyl) second-dimension column, and exhibited robustness to changes in the carrier gas flow velocity, oven temperature ramping rate, and secondary oven temperature offset. An average relative standard deviation of 2.7%, equal to a 95% confidence interval of 1.27 PEG-2I units, was obtained for the PEG-2I values of 72 environmental pollutants. Additionally, the system was found to be applicable over a wide range of boiling points (in the current case, from n-heptane to n-dotriacontane (C7-C32)) and can be used with various column dimensions. Changing the second-dimension column to either a narrower 0.1â¯mm column or a wider 0.25â¯mm column, yielded similar 95%-percentiles to that of the 0.18â¯mm column, differing by only 3.20 and 2.80 PEG-2I units, respectively. Moreover, methods for improving the system were suggested.
Related Topics
Physical Sciences and Engineering
Chemistry
Analytical Chemistry
Authors
Cathrin Veenaas, Peter Haglund,